1. Field of the Invention
This invention relates generally to drilling fluid cleaning systems, and more particularly to an apparatus and method for cleaning drilling mud which traps and isolates the mud so that solids of particular particle size in the mud are processed and removed in successive adjacent closed loop systems wherein each successive section of the system removes finer and finer solids until the mud reaches the desired properties.
2. Brief Description of the Prior Art
Effective control of solids in drilling mud in drilling mud systems has been a goal for the industry for many years. Some systems work better than others to achieve this goal.
To obtain the desired results that would give higher penetration rates, less contamination of formations, lower mud costs and less abrasives in the mud system to cause premature failure in rig equipment, many different systems have been tried, usually with poor to moderate results.
The systems that work best have a tremendous amount of very expensive and complicated machinery and require personnel to monitor the equipment and keep it working. If the operation requires dry solids from the system, even more equipment is required.
George et al, U.S. Pat. No. 4,462,416 discloses a method and apparatus for washing drilling cuttings which utilizes a pair of substantially common elevation tank compartments which include lower sump portions and a first tank compartment includes an inlet pipe portion for admitting drilling cuttings in a downward direction into the first tank compartment. The inlet pipe portion includes at least one lateral cleaning fluid jet and the first tank compartment includes additional horizontal cleaning fluid jets for directing jets of cleaning fluid through the drilling cuttings as they are admitted into the first tank compartment and subsequently directing jets of cleaning fluid through the cleaning fluid and drilling cuttings within the first tank compartment below the liquid level therein. The upper portion of the second tank compartment includes a vibratory screen-type separator positioned thereover and structure is provided for pumping fluent material from the sump of the first tank compartment to the separator whereby the larger size, cleaned cuttings will be separated from the other fluent material which passes downwardly through the separator and into the cleaning fluid within the second tank compartment.
Spruiell et al, U.S. Pat. No. 4,670,139 discloses a machine for cleaning drilling muds comprising a centrifuge desander operatively connected to a plurality of cooperating conical desilters to remove gases and separate materials of varying densities. Muds containing solid materials are pumped from the cleaning bed into an initial cyclone chamber, where, under increasing centrifugal force, the processed mud is separated into relatively heavier and lighter components, which are transmitted via separate pathways to twin chambers in the lower level compartment of a particle separating drum. The first chamber of the drum receives heavier materials and transmits them to a large desander cone where the heaviest impurities are removed; the second drum chamber receives the lighter components which are further separated and delivered to a network of desilter cones which output properly cleansed mud. The purified output of the large desander cone is transmitted directly back into the cleaning bed reservoir. Freed air and gasses are discharged at controlled rates to be burned or dispersed into the environment through a third stage, which is in fluid flow communication with the initial stage and the desilter stage.
The present invention is distinguished over the prior art in general, and these patents in particular by an apparatus and method for cleaning, desanding, and desilting drilling mud that contains unwanted solids which utilizes an enclosure divided into a plurality of compartments connected with a system of vibratory screen shaker separators, desanders, and desilters. Drilling mud is separated by a primary vibratory shaker into coarse solids which are discarded and screened liquid mud which enters a first compartment and is further separated by a desander cyclone into a lighter liquid mud faction and a heavier liquid mud faction. The lighter faction is sent back to the first compartment and recycles, the heavier faction is further separated by a second vibratory shaker and enters a second compartment, and the solids are discarded. The liquid mud from the second compartment is further separated by manifolded desilter cyclones into a heavier faction and a lighter faction. The lighter faction is sent back to the second compartment and recycles, the heavier faction is further separated by a third vibratory shaker and enters a third compartment, and the solids are discarded. The liquid mud from the third compartment is further separated by a high-speed desilter cyclone into a heavier faction and a lighter faction. The lighter faction is sent back to the third compartment and recycles, the heavier faction is further separated by a fourth vibratory screen shaker into desilted dry solids and desilted liquid mud. The four times screened, desanded and twice desilted liquid mud is then used in the active mud system.